The disclosed technology relates to polymer-containing lubricant formulations useful for lubricating mechanical devices, especially those involving lubrication of gears.
U.S. Patent Application US-2011-0190182, Price et al., Aug. 4, 2011, earlier published as WO2010/014655, discloses a copolymer comprising units derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified with certain alcohols which may be used to provide, among other properties, improved viscosity index control to a lubricant. It may be used along with other performance additives, including, among others, (other) viscosity modifiers such as polyolefins. It may be used with an oil, which may be a synthetic lubricating oil including, among others listed, polybutylenes.
PCT Publication WO2011/146692, Nov. 24, 2011, discloses a lubricating composition containing a copolymer comprising units derived from monomers (i) an α-olefin and (ii) an ethylenically unsaturated carboxylic acid or derivatives thereof esterified and amidated with an alcohol and an aromatic amine.
A primary role of a lubricant in a mechanical device is to prevent direct metallic contact which would result in adverse friction, reduced fatigue life and rapid wear. As the viscosity of a fluid is reduced so is the film thickness, which is required for separation of moving parts. Under moderate to high load (typically 0.3 to 3.0 GPa) the mechanism of film protection is referred to as elastohydrodynamic (EHD) lubrication. EHD film thickness can be improved by the addition of polymeric materials or viscosity modifiers to a fluid. However, such additives may lead to relatively low efficiency in the power transfer between surfaces such as a gear. On the other hand, certain lubricant additives are effective at providing good efficiency through lower fluid viscosity, higher VI, lower operating temperature or low traction but may provide inadequate EHD film thickness. It is desirable to have a lubricant that provides a good combination of power transfer efficiency and EHD film thickness.